Relay device



Dec. 24, 1929. w. KOCH 1,740,465

RELAY DEVICE Filed Feb. 4, 1927 WITNESSES; INVENTOR Walther- Koch.

Patented Dec. 24, 1929 UNITED/STATES PATENT; OFFICE wAL'rmm xocn, or BERLIN, GERMANY, nssrenoa T WESTINGHOUSE ELECTRIC a murac'rumne comrnmr, A CORPORATION or PENNSYLVANIA RELAY DEVICE Application filed February 4, 1927, Serial No. 185,839, and in Germany February 4, 1926.

My invention relates to electrical protective systems and to relay devices employed therein for the protection of associated electric circuits.

One object of my invention is to provide a relay of the type which adjusts its time of operation according to its nearness to, or distance from, a fault in the main system.

Another object of my invention is to proo vide a protective relay and relay system in which t e time of operation is accelerated in accordance with the variation of the ratio of the circuit current to the normal voltage from a predetermined value.

Another object of my invention is to provide a relay in which the time element of operation is modified by the voltage of the circuit at the region from which the relay is energized.

Relays of the impedance or voltage-re-' straint type have been employed in which a current element serves to actuate a trip ping contact at a speed that is roportional to the value of the current. t the same 125 time, a volta e element operates to restrain the action of t e current element in proportion to the voltage of the circuit at the region from which the current is derived to energize the current element. In relays of that type, if the voltage is normal, the current element is restrained, and its operation is modified according to the normal values of current and of voltage for which the relay is adjusted.

It is understood that upon the occurrence of a fault in a power system, there is a potential gradient from the source of current to the location of the fault. The voltage of the systerm at the location of the fault is at a minimum value and is of gradually increased value in portions of the circuit that are more remotely disposed from the fault.

Since the operation of the relay is dependent upon the restraint imposed by the voltage element, it becomes apparent t at the relay which is connected to the portion of the circuit that is nearest to the fault will have minimum restraint imposed by its voltage element, and will consequently, operate most quickly. If all the relays connected to the system are adjusted to traverse operating paths of equal length, the relay (bat is nearest to the fault will operate first to close its contacts. lays operate automatically and selectively to adjust their respective operating intervals so as to accelerate that relay associated with or nearest to the portion of the system in which the fault exists to isolate that faulty portion.

An object of my invention is to provide a relay of such general type, which will be more sensitively responsive to the current and voltage conditions in the system and to isolate afaulty portion thereof. To that end, I provide a relay embodying a current actuating element and a voltage restraining element, with means for modifying the effective restraint exercised by the voltage element upon the current element, in operating the relay. In one modification, I provide a movable fulcrum between the current element and the switch controlled thereby, the movable fulcrum being adjustably positioned by the voltage element according to the value of the voltage in the associated region of the main system. In another modification in which the current element acts upon an induction disc of the type at present generally used for protective relays, the voltage element modifies the position of the current element with respect to the disc.

In the first mentioned modification, as the voltage diminishes, the movable fulcrum is shifted, by a suitably disposed spring, to a position which multiplies the torque of the current actuating element. In the second mentioned modification, a spring similarly moves the current element further from the center and out towards the periphery of the disc, whereby the torque upon t disc is correspondingly increased to acce erate its operation.

The invention may be better understood upon reference to the accompanying drawing in which Fig. 1 illustrates in simplified schematic form the construction of one embodiment of a relay constructed in accordance with the principles of my invention; and

Fig. 2 is a plan view of a schematically illus- On this basis of operation, the re-' trated relay of another modification embodying the principles of my inventlon.

A portion of a main circuit 11 1 s arranged to be isolated from an ad o ning portion of the system by means of a circuit interrupter 12 upon the occurrence of a fault in the circuit 11, as illustrated, for example, at the point A. A'relay 13 is provided to selectively control the interrupter 12 according to its nearness to the location of the fault, and comprises a current coil 14 which operates through a lever arm 15 to close a contact 16 in the circuit of the trip coil of the interrupter 12. A suitable timing device is associated with the trip coil 16, and is illustrated, merely by wayvof example, as consisting of an induction disc 17 and a permanent drag magnet 18. Movement is imparted to the disc 17 by the arm 15 through a suitable flexible connecting means 19.

The effect of the current element 14 upon the contact member 16, through the arm 15, is controlled and modified by a voltage element 21 according to the value of the voltage of the circuit adjoining the interrupter 12. The current element 14 is also energized from the circuit at a point adjoining the interrupter through a current transformer 22, and the relay 13 therefore responds to the current and voltage conditions in the circuit adjoinin the interrupter 12. The restraint of the v0 tage element 21 upon the current element 14 is introduced through a movable fulcrum 23 which serves as a medium to vary the length of the arm through which the current element acts as compared with the length of the arm which acts upon the contact member 16. When the voltage is normal, the movable fulcrum is held in its extreme lefthand position so that the effect of the current element 14 in actuating the contact member 16 is relatively small. If the voltage diminishes, however, a spring 24 moves the fulcrum 23 farther towards its righthand side and increases the lever arm with which the current element is associated, thereby increasing the actuating force upon the contact member 16.

When a fault occurs in the section closely adjoining the interrupter 12, as at the point A, the current element will be greatly energized, due to the fault current, but the voltage element will be energized to a degree less than normal, depending upon the nature of the fault. If the fault be considered to be a low resistance short circuit, the voltage will be very small and, consequently, the spring will operate to shift the fulcrum to the extreme righthand position. The effect of the current element on the contact member will thus be greatly magnifiedand the operation of the contact member will be correspondingly accelerated.

It becomes apparent, therefore, that the position assumed by the movable fulcrum varies according to the value of the voltage which, by reason of the potential gradient established between the source and a fault, will vary according to the distance from the fault. By means of the adjustable fulcrum, the relay is rendered more sensitive and more quickly responsive to faulty conditions, thereby selecting and operating the interrupters nearest to the fault in minimum time.

The modification that is illustrated in Fig. 2 comprises an induction disc of the type now generally employed in protective relays and current elements 31 for effecting movement of the disc to operate a contact member 32 to control an external tripping circuit for an interrupter. A dra magnet 33 is provided to introduce a time element in the operation of the relay and to prevent drifting of the disc during non-operating intervals.

The effect of the current element 31 upon the disc 30 is controlled by a voltage element 34 which cooperates with an anchored spring 35 to adjust the position of the current element 31 in a region between the cen ter of the disc and its eriphery, throu h the medium of a pivoted support 36. T e operation of this relay is apparent from the explanation already iven with respect to the rela shown in ig. 1 and illustrates in a di erent embodiment the manner in which the actuating force or torque of the current element may be multiplied or diminished, according to the value of the voltage of the associated region of the circuit.

My invention is not limited to the specific modifications that are illustrated, since the principles are sufficiently Well disclosed herein to enable those skilled in the art to applyit generally to relays of different constructlon.

I claim as my invention:

1. An electric relay comprising a contact member for controlling an external circuit, a time delay device associated therewith, a current element adapted to be energized from an external power c1rcuit and to effect movement of the contact member and means responsive to the voltage of the external power circuit for introducing a multiplying factor in the effect of the current element upon the contact member.

2. An electric relay comprising a current element to be energized from an external circuit, a contact member controlled by the current element and provided with means for introducing a time element in its operation, and a voltage element to be energized from the external circuit and operative to introduce a multiplying factor in the effect of the current element on the contact member in proportion to the voltage.

3. An electric relay comprising a movable contact member provided with means for introducing a time function in its operation, a current element. for actuating the contact member, and a voltage element for introducing a multiplying factor in the effective force of the current elementin accordance with the energization of said voltage element.

4. An electric relay comprising a contact member, actuating means having a time function in its operation for controlling the contact member, a current element, a pivoted member through which the current element operates the actuating means and a voltage element for controlling the position of the fulcrum of said pivoted member to modify the influence of the current element upon the actuating means.

In testimony whereof, I have hereunto subscribed my name this 13th day of January,

VALTHER KOCH. 

